The Prophet (ﷺ) said: There is no divorce except in what you possess; there is no possession, there is no sale transaction till you possess. The narrator Ibn as-Sabbah added: There is no fulfilling a vow till you possess.
Sunan Abi Dawud Book 13, Hadith 16
← Previous Hadith The Prophet (ﷺ) said: The divorce of a slave-woman consists in saying it twice and her waiting period is two menstrual courses (qur') AbuAsim said: A similar tradition has been narrated to me by Muzahir and al-Qasim on the authority of Aisha from the Prophet (ﷺ), except that he said: And her waiting period ('iddah) is two courses.

Abu Dawud said: This tradition is obscure.

Sunan Abi Dawud Book 13, Hadith 15 Next Hadith → The above tradition has also been transmitted by ‘Amr bin Shu’aib through a different chain of narrators to the same effect. This version adds “If anyone swears an oath to do an act of disobedience to GOD, his oath is not valid, and if anyone swears an oath to sever relationship, his oath is not valid(i.e., he must not fulfill it)

Sunan Abi Dawud Book 13, Hadith 17